Recent interest in the industrial manufacture of ethanol and other organic chemicals from saccharides and poly-saccharides has lead to the utilization of surplus grain as a source of these chemicals by enzyme-fungal or bacterial conversion of the sugars contained therein. The starting grain is, however, in the food chain and its diversion for other uses is arguably not in the best interests of society. Ghose, U.S. Pat. No. 3,642,580, Mandels and Kostick, U.S. Pat. No. 3,764,475, and Gauss et al., U.S. Pat. No. 3,990,944 have disclosed processes whereby cellulose can be enzymatically converted to simple sugars and thence to ethanol.
The key to this conversion has been to free native cellulose from the lignin intimately bound thereto and to expand the cellulose structure to allow accessibility of the solid to the enzyme needed for conversion.
In order to improve the reactivity of cellulose to hydrolysis to obtain sugars, pretreatment of materials containing cellulose with caustic soda, ammonia, peracetic acid or hydrogen peroxide prior to the hydrolysis has been proposed. Attempts to parallel the hydrolysis procedure to that of starchs have not been successful since cellulose is a difficult material to hydrolyze compared with starch, so pretreatment using the above mentioned substances is considered very important before hydrolyzing cellulose-containing materials.
However, pretreatment by alkali or acid as described above is accompanied by problems in recovery or disposal of waste alkali or waste acid. In addition, corrosion of the equipment used for the pretreatment inevitably occurs. When hydrogen peroxide is used for pretreatment the disposal and corrosion problems are minimized, but drawbacks are that hydrogen peroxide costs more than alkali or acid and a greater amount is needed for the effective pretreatment. Furthermore, hydrogen peroxide does not more substantially enhance the susceptibility of cellulose to enzymic attack than do alkali or acid, so it has not yet been put into practical use.
It is known that various metal salts such as salts of Fe.sup.++ (Fenton reagent), Cu.sup.+, Cu.sup.++, Co.sup.++ or other metal compounds such as V.sub.2 O.sub.5, OsO.sub.4, WO.sub.3, MoO.sub.3, SeO.sub.2, TiCl.sub.4, and CrO.sub.3 are used with hydrogen peroxide to bleach fibrous materials such as cotton, linen and pulp. However, use of the above metal compounds and especially manganese compounds together with hydrogen peroxide for the improvement of hydrolysis of cellulose by enzyme has not been reported.